For cables in tunnels, this is the temperature of the air inside the tunnel.

For cables in troughs, this is the temperature of the air inside the trough.

Symbol
$\theta_{\mathrm{at}}$
Unit
°C
Formulae
 $iteration$ cables in tunnel $\lambda_{\mathrm{t}} \left(\Delta \theta_{\mathrm{tr}} + \theta_{\mathrm{air}}\right) + \theta_{\mathrm{at_{\mathrm{0}}}} \left(- \lambda_{\mathrm{t}} + 1\right)$ cables in trough
Related
$\Delta \theta_{\mathrm{tr}}$
$\lambda_{\mathrm{t}}$
$\theta_{\mathrm{air}}$
$\theta_{\mathrm{at_{\mathrm{0}}}}$
Used in
$I_{\mathrm{c}}$
$k_{\mathrm{air}}$
$\nu_{\mathrm{air}}$
$\mathrm{Pr}_{\mathrm{air}}$
$T_{\mathrm{sa}}$
$\theta_{\mathrm{c}}$
$\theta_{\mathrm{de}}$
$\theta_{\mathrm{hs}}$
$W_{\mathrm{hs}}$